1. Field of the Invention
The invention pertains to a damping valve with a directionally-dependent cross section including a damping valve body with an outlet side and at least one through channel; a first cover disk loaded toward the outlet side and having at least one hole aligned with the at least one channel; and a nonreturn valve disk which enables flow of damping medium in one direction through the at least one hole and blocks flow of damping medium in the opposite direction through the at least one hole.
2. Description of the Related Art
In the design of damping valves for vibration dampers, it can be advisable, especially for reasons of comfort, to provide differently sized cross sections, also called advance cross sections for the different flow directions of the damping valve. Several design variants of a damping valve are disclosed in GB 2,113,355. In the variant according to FIG. 2, a nonreturn valve disk with a C-shaped cutout is used, the inside diameter of this disk being held firmly under tension against a piston. An outer ring-shaped part of the nonreturn valve disk can undergo elastic deformation with respect to the central, circular ring-shaped clamping surface. A sealing disk is located concentric to and radially outside of the outer ring-shaped part of the nonreturn valve disk. When damping medium arrives at the outer ring-shaped part of the nonreturn valve disk from the direction of the channels, which open out into a ring-shaped channel, the outer ring-shaped part is pressed against a cover disk, which blocks the flow connection with the working space. When the damping medium arrives from the direction of the cover disk, the outer ring-shaped part is lifted from the cover disk and releases an advance cross section. This design of a directionally dependent advance cross section, which appears quite simple at first glance, turns out to have some problems in practice. For example, there must be a gap between the outer ring-shaped part and the sealing disk radially outside it. Because of its radial area, this gap has a significant effect on the functionality of the advance cross section. In addition, the outer sealing disk is made of thicker material than the valve disk. As a result, the cover disk is deformed at least slightly in the manner of a disk spring, so that the nonreturn valve disk must undergo a comparatively large amount of deformation, which in turn demands a larger gap between it and the radially outer sealing disk. The nonreturn valve disk is subjected to considerable compressive forces in the opening direction, that is, in the direction toward the ring-shaped channel, but forces are not absorbed in any way by the piston or by the radially outer sealing disk. The service life of the nonreturn valve disk therefore tends to be limited.
In the variant according to FIG. 7 of GB 2,113,355, a simple closed nonreturn valve disk (without a cutout) is used, which is supported on a sealing disk, which has three arc-shaped openings. The sealing disk is pretensioned toward the piston on its inner and outer diameters; whenever it is desired to achieve a degressive characteristic according to FIG. 5, the surface of the piston will have a certain height offset, i.e., areas at two different heights, so that the outer diameter will be tensioned firmly against the piston. As a result, an undefined gap is formed between the bottom surface of the sealing disk and the nonreturn valve disk; this gap also has an effect on the advance cross section. In this variant, furthermore, there is no stop surface present to limit how far the nonreturn valve disk can travel in the opening direction.